1. Field of the Invention
The present invention relates to the field of display technology, and in particular to a method for manufacturing a quantum dot color filter.
2. The Related Arts
With the continuous development of the display technology, people increasingly demand higher and higher quality of displaying. Quantum dots (QDs) are nanometer semiconductor particles in the form of spheres or similar to spheres made of elements of II-VI groups or III-V groups, having a particle size between several nanometers and tens of nanometers. Since the particle size of QDs is less than or close to the exciton Bohr radius of the corresponding material, an quantum confinement effect is generally involved, where the energy band structure is changed from quasi-continuity of the body material to the discrete structure of the quantum dot material, making the quantum dots exhibiting unique behavior of stimulated emission of light. When the size of the QDs is decreased, the energy band gap becomes increased so that the energy required for exciting the QDs and the energy released from the excited QDs returning back to the ground state are increased correspondingly, exhibiting a “blue-shifting” phenomenon of the excitation of the QDs and the fluorescent spectrum. By controlling the size of the QDs, the emission spectrum thereof may be made covering the entire range of visible light. For example, when the size of cadmium selenide is decreased from 6.6 nm to 2.0 nm, the luminescence wavelength “blue-shifts” from red light zone of 635 nm to blue light zone of 460 nm.
Quantum dot materials have advantages, such as concentrated luminescence spectrum, high color purity, and luminescence color being easily adjustable through the size, structure, or composition of the quantum dot materials. Such advantages allow for applications in display devices to effectively improve the color gamut and color restorability of the display devices. For example, patent documents including CN 102944943 A and US 2015/0002788 A1 propose technical solutions of using quantum dot layers having a pattern structure to replace color filters for color displaying. However, such patent documents do not disclose the ways of patterning the quantum dot layers
In making a quantum dot pattern of a conventional quantum dot display device, it is common to mix red, green, blue quantum dot materials respectively with red, green, and blue quantum photoresists, followed by exposure and development to form a patter including quantum dots. However, such a process requires the red, green, and blue quantum dots to be mixed with red, green, and blue quantum dot photoresists first and also requires three photolithographic operations, making the process complicated, and it also need to develop red and green quantum dot photoresists at the same time, making the development of quantum dot photoresists difficult. Besides the above method, quantum dot patterns may also be formed by means of transfer-printing and screen printing. However, the quantum dot patterns formed with transfer-printing have poor resolution, where edges of the patterns are in a serrated form and the adhering power between the quantum dot layer and the base requires being further improved. Inkjet printing may also be used to form patterned quantum dot layer and such a method has a severe requirement for the inkjet printing device. In addition, there is still technical barrier to maintain stability of the drops of ink jet and the precision of printing, making it not possible for use in mass production.